Clean up routes.rb a tiny bit

I'm a bit of a nazi, can't stand all that boilerplate in a file.
Add a migration for tags

Decided it would be easier to work with the existing sqlite database and use a
more traditional join table approach: The posts table has no references to
tags, the tags table is just a bare table with an id and name, and a join
table (posts_tags) has a foreign key to posts and tags.
Add Tag model
Add jquery-ui-rails for TagIt

Pretty sure this is included by default in new rails 3 projects, so this might be
completely unecessary.
Add #tags and #posts methods to Tag, Post models
Add create / edit UI for tags

Not showing up anywhere outside the admin area, but you can create them.
Break post.js into separate files

The way we handle tags will be different between editing and viewing. I suspect
the style of tags will also be very different. Need to start thinking about how
I want to style these after I get search working.
Clicking on tags shows all matching posts

Thinking about consolidating some of the repeated view code into some shared
views, but I fear that might be premature.
Include tags on root page
Style tags
Include tags on tag pages
Change tag container style on admin pages

It was hard to see that you could edit this otherwise.